Stabilized organic sulfur-containing compounds



United States Patent STABILIZED ORGANIC SULFUR-CONTAININ G COMPOUNDS Theodore J. Peters, Jr., Somerville, N. L, assignor to Esso Research and Engineering Company, a corporation of Delaware N Drawing. Application May 13, 1952, Serial No. 287,605

3 Claims. (Ci. 260-l37) This invention relates to an improved method of minimizing the evolution of hydrogen sulfide from organic sulfur-containing compounds from which hydrogen sulfide is normally evolved.

Many organic sulfur-containing compounds normally evolve hydrogen sulfide during storage, transportation or use. Because of the obnoxious odor of the hydrogen sulfide gas, this evolution is quite objectionable. Fre quently, it is desired to use such compounds as additives for mineral oil compositions, such as lubricating oils, to impart to the composition various desired properties such as extreme pressure properties, anti-corrosive properties, detergent properties and the like. However compositions containing even small amounts of unstable sulfur-containing compounds will evolve hydrogen sulfide. Users of such compositions object to these odors, and consequently the saleability of the product is impaired. Many organic compounds that have been sulfurized by treatment with sulfur, sulfides of phosphorus and the like show this characteristic unstability with respect to hydrogen sulfide evolution. 7

Numerous attempts have been made' to stabilize such sulfur-containing compounds or compositions including these compounds. Neutralization of acidic sulfur-containing materials with basic reagents frequently fails to give a stable product. In some cases, inhibitors have been added which tend to minimize HzS evolution. Another procedure that has Wide spread useage involves blowing the material with air in order to stabilize the material against l-lzS evolution. Treatment with air, however, is costly and time consuming because extensive treating is required to form a fairly stable product. Frequently, treating times of 1 to 3 days or more are re-' quired even at high air rates. Treatment with oxygen or gases containing high concentrations of oxygen is very dangerous due to explosion hazards existing with even small amounts of hydrocarbons. Furthermore, the airtreated material often proves to be unstable when it is heat-. ed to elevated temperatures in subsequent use. It is an object of the present invention to provide a rapid, safe, effective stabilizing method that overcomes the disadvantages of air blowing and eliminates or minimizes the need of using expensive additives for inhibiting HzS evolution.

In accordance with the present invention, liquid organic sulfur-containing compounds are treated with a relatively small amount of an oxide of nitrogen such as nitric oxide, nitrogen dioxide, nitrogen trioxide, nitrogen tetroxide, nitrogen pentoxide and their mixtures. A mixture of nitric oxide and nitrogen dioxide is particularly suitable. Briefly, the liquid material to be treated is contacted with the vaporous oxide of nitrogen in an amount suflicient to eliminate or minimize subsequent H25 evolution but insufficient to cause a substantial loss in total sulfur content. The treating step may be carried out at atmospheric temperature and pressure conditions, although temperatures such as in the range of about 5.0 up to 250 1 F. and higher may be used to obtain more complete 2,767,163 Patented Oct. 16, 1956 treating. The treatment should be carried out in the substantial absence of water to avoid formation of acids of nitrogen.

The reason for the effectiveness of oxides of nitrogen for stabilizing the sulfur-containing organic compounds is not entirely understood, and it is not desired to be bound by any theory of action. The treatment is carried out under conditions such that substantially no sulfur is removed from the material being treated, but loosely bound or unstable sulfur is evidently affected in some manner. Apparently, the oxide of nitrogen reacts to some extent with the material being treated, and perhaps in this way forms stable compounds that will not subsequently decompose to H25. It is possible that unstable thiol groups are converted to stable disulfides. The amount of oxide of nitrogen needed to stabilize the material is so small, however, that any chemically bound nitrogen remaining in the treated product is not deleterious. In some cases, the nitrogen entering the treated compounds seems to be beneficial when the sulfur-containing material is used as a lubricant anti-oxidant or the like.

In carrying out the process, any suitable apparatus permitting intimate contact between the material being treat-.

packed tower in countercurrent relationship with down flowing sulfur-containing compound, the tower being of the conventional scrubber type containing Raschig rings, disc and donut contactors, and other types of packing. If desired, the gas may be blown into a tank containing the material to be treated, and the material may be agitated by a stirrer or other type of agitating device. Such contacting devices are well known to the art.

In the event the sulfur-containing organic compound is extremely viscous, improved contacting may be obtained by operating at elevated temperatures as heretofore mentioned or by diluting the material to be treated in a suitable solvent that will lower the viscosity thereof. For example, if the material is to be used as a lubricant additive, it may be dissolved in a lubricant base stock and the blend treated as described above. The solvent may be of a difierent boiling point so that it may be easily separated in a subsequent distillation operation.

The oxide of nitrogen may be used in a relatively pure blended with air, and the air-nitrogen oxide mixture.

used for treating the unstable material. The oxide of nitrogen may be generated by any suitable means Well known to the art, and the gaseous oxide should be' substantially free of water or acids of nitrogen.

The amount of oxide of nitrogen needed to effect stabilization will vary depending on the type of material being treated, the efiiciency of contact during the treating step, treating rates, treating temperatures and other conditions. The amount may be as low as about 0.1 cubic foot per hour per gallon of sulfur-containing material being treated providing the contact time is sufiicient. Generally, rates in the order of about 3 to cubic feet of vaporous oxide of nitrogen per hour per gallon of liquid feed will be sumcient to effect stabilization. Under these conditions, contact times may range from about 5 minutes up to one to ten hours or more.

The present invention has particular application to the improvement of sulfurized organic compounds prepared by treating organic compounds with sulfur, sulphosphorus sesquisulfide, etc., their mixtures and other h the like.

2,7a7,1as

sulfurizin g'agents well known to the art. The organic compounds that are sulfurized are also well known to the art. These include the hydrocarbons such as olefins, olefin polymers, diolefins, acetylenes, aromatics, petroleum fractions such as lubricant-distillates, residua, petrolatums, Terpenes such as dipentene, pinenes, and the like are also sulfurized to form eifective lubricant additives and the like, ,the products generally being unstable.

A Other organic compounds that may be sulfurized in- 'clude'the organic acids, particularly the highe'r'carboxylic acids, esters, petroleum acids, naphthenic acids, higher alcohols, ketones and aldehydes, and other oxygen con taining compounds Phenolssuch as the alkyl phenols, alkyl phenol sulfides and the like are particularly valuable as feed stocks for sulfurization to make lubricant additives. ..Other organic compounds include amines, fatty oils of animal and vegetable origin such as sperm oil, degra-s, andthe like.

Frequently, the acidic sulfurized organic material is treated with a basic material for neutralization purposes or to introduce a metal component into the material. The treatment of the present invention may be applied before neutralization. It is also effective in preventing HzS evolution from neutralized materials in those cases where the neutralized compound evolves HzS as here? tofore described. It is also known that sulfurization of metal salts of organic compounds produces unstable materials. Treatment of such materials with an oxide of nitrogen is also quite effective. V i

The improved products of the present invention may be used as additives for mineral oils such as lubricating oils, greases, heating. oils, gasolines and the like. Amounts in the range of about 0.01 to by weight may be used depending on the property of the composition to be improved. The stable agents find use as antioxidents and corrosion inhibitors, extreme pressure additives, detergents, sludge dispersers and the like.

When the sulfurized materials treated in accordance with the present invention are used in such compositions, the

resulting blends have substantially no tendency to evolve H2S even when subjected to elevated temperatures.

As heretofore mentioned, the sulfurized organic corn- Thus, a lupound may be diluted before treatment.

bricant base stock containing in the range of about to 50% by weight of the unstable compound may be treated with an oxide of nitrogen as described above. The treated concentrate is then stored and shipped in that form. A finished lubricant is prepared by blending the needed amount "of the concentrate with a lubricant base stock to obtain any desired concentration. The finished lubricant may comprise, in addition to the treated sulfur-containing material, other additives well known to'the art. such as viscosity index improvers, detergents, etc.

. The practice of the present invention will be illustrated in connection with the following examples, although the invention is not to be construed as being limited by these examples in any way.

EXAMPLE I phenol sulfide with 4% by weight of phosphorus pentasulfide wastreated with a blend of nitric oxide (NO) and nitrogen dioxide (N02) in accordance with the present invention. A series of runs were carried out in which thephosphosulfurized material was placed in a flask equipped with'a stirrer, and the dry gaseous mixture was bubbled into the stirred material. The treated material was heldat a temperature of 122F. The oxides of nitrogen were charged at various rates with total contact times varying from-about 3 to 11 minutes. In each case, the treated material was blown with air in order to insure removal ofany free N203, about 100 volumes of, purge air per'volumegof. treated material about 212 F. and then filtered thru a diatomaceous earth filter aid.

The product from each run was then tested tori-12S evolution tendencies. This was'carried out by the following procedure:

800 mls. of the blend to be tested were placed in a small-rnouth 1 quart bottle; An aluminum foil covered stopper was placed in the mouth of the bottle and the contents raised to 100"v F. for 1 hour. At the end of this period, a filter paper wet with a saturated solution of aqueous'lead acetate'was placed over the mouth of the bottle and allowed to remain for 5 minutes. The filter paper was removed and the extent of staining compared with a standard.

The extent of staining of the paper is rated on a scale of from 0 (no staining) to 10 (complete black sulfide film). The material is considered to have a satisfactory stability if the H25 rating is below about 6. A D. N. P. (Did Not Pass) is given when the rating is above about 6. The untreated product gave a D. N. P. rating. The results of the. runs are shown in Table I below; r

Table I Treating Conditions Run No. bro-N0,

Rate, Cu Time, Temp., HzS Rating Ft./Hr./ Minutes F. on Product Gallon 22. 2 3 122 D. N. P. 19.2 10 122 Pass. 7 15. 5 5 122 D. N. P. 11.3 11 V 122 Pass.

Under the conditions employed, treating times of from 3 to 5 minutes with NO-NOz rates of about 15 to 22 cubic feet per hour per gallon .were insufficient to form.-

a satisfactory product. NONO2 rates of from about 10 to 20 cubic feet per hour per gallon with treating times of about 10 minutes were suflicient to form a product having excellent H28 stability. in contrast, several'run-s were carried out in which air was employed J At an air rate of 5.3 cubic,

as the contacting agent. feet per hour per gallon, 43'hours treating time was needed to forma satisfactory product. At'an air rate of cubic feet per hour per gallon, 17 hours treating time was necessary to form a product passing the H25 evolution test. The time required to stabilize with air was more than an order of magnitude greater than the time required when using'an oxide of nitrogen.

Comparative analysis of feedand product from Run 'B (TableI) are. shown in Table II below:

Table II ANALYSIS OF FEED AND PROD UCT, RUN B Gomponent,wt. percent Feed Treated Product Barium". "8.3 7 $.31 Sulfur 6.82 5.73 Phosphorus 0. 967 0. 98 Nitro en V '0 0. 23

It is seen that the total barium, sulfur and phosphorus contents of the material were substantially unalfectedand that a small. amount of chemically boundnitrogen re-' mained in the product. It was also found that the nitrogen oxide treatment did not impair the efiectiveness of the product from Run B as a lubricant additive from,

the standpoint of bearing. corrosion inhibition properties and copper strip stainingproperties. Indeed, the corro sion inhibition properties of the treated material were somewhat superior to those of both the untreated and the air-blown materials.

EXAMPLE H A sample of sulfurized dipentene, which had an H28 rating of was treated with an NONO2 mixture at a rate of about 9.0 cubic feet per hour per gallon for 17 minutes. An HzS rating of 0 was obtained on the treated product. The treatment was carried out under substantially the same conditions employed in Example I. A lubricating oil containing 2.5% by weight of the untreated sulfurized dipentene did not pass the H23 evolution test. An oil blend containing 2.5% by weight of the sulfurized dipentene treated with the oxides of nitrogen gave an HzS rating of 0.

What is claimed is:

1. In a method for preparing organic sulfur-containing compounds useful as lubricating oil additives and selected from the group consisting of sulfurized hydrocarbons and phospho-sulfurized metal salts of alkyl phenol sulfides, the improvement in accordance with which the odor of said organic sulfur-containing compounds is improved which consists essentially of contacting said organic sulfur-containing compounds selected from the group consisting of sulfurized hydrocarbons and phospho-sulfurized metal salts of alkyl phenol sulfides with a vaporous oxide of nitrogen at a temperature of about to 250 F. for about 5 minutes to 1 hour to thereby substantially reduce the evolution of hydrogen sulfide from said organic sulfur-containing compound without removing substantially any sulfur therefrom, said contacting being carried out in the substantial absence of water and employing about 3 to cubic feet of vaporous oxide of nitrogen per hour per gallon of said organic sulfur-containing compound.

2. A method as in claim 1 wherein said oxide of nitrogen is a mixture of NO and N02.

3. A composition as in claim 1 wherein said sulfurized organic compound is a phosphosulfurized barium salt of an alkyl phenol sulfide.

References Cited in the file of this patent UNITED STATES PATENTS 522,028 Price June 26, 1894 1,933,748 Morrell Nov. 7, 1933 1,962,181 Egloif June 12, 1934 2,009,898 Morrell July 30, 1935 2,384,146 Wallace Sept. 4, 1945 2,483,600 Stucker Oct. 4, 1949 2,497,097 Roberts Feb. 14, 1950 

1. IN A METHOD FOR PREPARING ORGANIC SULFUR-CONTAINING COMPOUNDS USEFUL AS LUBRICATING OIL ADDITIVES AND SELECTED FROM THE GROUP CONSISTING OF SULFURIZED HYDROCARBONS AND PHOSPHO-SULFURIZED METAL SALTS OF ALKYL PHENOL SULFIDES, THE IMPROVEMENT IN ACCORDANCE WITH WHICH THE ODOR OF SAID ORGANIC SULFUR-CONTAINING COMPOUNDS IS IMPROVED WHICH CONSISTS ESSENTIALLY OF CONTACTING SAID ORGANIC SULFUR-CONTAINING COMPOUNDS SELECTED FROM THE GROUP CONSISTING OF SULFURIZED HYDROCARBONS AND PHOSPHO-SULFURIZED METAL SALTS OF ALKYL PHENOL SULFIDES WITH A VAPOROUS OXIDE OF NITROGEN AT A TEMPERATURE OF ABOUT 50* TO 250* F. FOR ABOUT 5 MINUTES TO 1 HOUR TO THEREBY SUBSTANTIALLY REDUCE THE EVOLUTION OF HYDROGEN SULFIDE FROM SAID ORGANIC SULFUR-CONTAINING COMPOUND WITHOUT REMOVING SUBSTANTIALLY ANY SULFUR THEREFROM, SAID CONTACTING BEING CARRIED OUT IN THE SUBSTANTIAL ABSENCE OF WATER AND EMPLOYING ABOUT 3 TO 100 CUBIC FEET OF VAPOROUS OXIDE OF NITROGEN PER HOUR PER GALLON OF SAID ORGANIC SULFUR-CONTAINING COMPOUND. 